From the U.S. Pat. No. 5,356,420 a puncturing device is known comprising a sleeve and a push button positioned at one sleeve end. The other sleeve end terminates with a bottom with an opening therein. Inside the sleeve a piston is slidably positioned, terminating with a push rod at the end closer to the push button, and with a puncturing tip at the end closer to the bottom opening. Inside the sleeve, between the push button face and the piston a drive spring is located, and between the piston and the sleeve bottom a return spring is placed. The piston comprises wings located on its outer perimeter, which wings rest on an internal projection of the sleeve, and when the device is used, the wings get broken, and subsequent re-use of the device is not possible.
In the U.S. Pat. No. 5,439,473 is disclosed a lancet designed for puncturing the patient's skin for collecting small blood samples. The lancet has an elongated body wherein a movable member is placed slidingly along the body axis, while the body has a top opening for the lancet push button, and a bottom opening for the piercing blade. The movable member consists of a flat spring, one end of which is joined to the push button. The push button has two upper arms perpendicular to its surface, and these arms have hooked ends placed in oblong openings of the body side walls. The other end of the movable member flat spring is joined with a holder wherein the piercing blade is fixed. The lower portion of the holder has two lower arms parallel to the upper arms. The lower arms have, moreover, upwardly directed, triangle shaped ends, which rest upon the lower edges of the oblong openings of the body walls. All parts of the movable member are made of plastic. When the patient's skin is being punctured, the lancet push button is pressed, so the flat spring of the movable member is tensed, and hooked ends of the upper arms press against the ends of the lower arms of the movable member. Next, the lower arms get released, the flat spring rebounds, and the patient's skin is punctured by the piercing blade, which passes through the body bottom opening. After puncturing the skin, the flat spring assumes its free position, and the piercing blade retracts into the inside of the lancet body.
Further, the U.S. Pat. No. 5,755,733 discloses a lancet device consisting of a lancet assembly and a holder linked to the lancet assembly, wherein the lancet assembly has a lancet with a piercing portion, and an ejector which pushes the lancet out. In this known lancet device, the lancet piercing portion is covered with plastic material.